Water Strider

Family:Gerridae

Description: Have you ever been looking at a pond or vernal pool and thought you saw a bug walking on the water? Was it moving so quickly it seemed to glide across the surface? Seems far-fetched and a trick of the eye, right?

What you saw on the surface of the pond was a water strider. They are small insects that evolved for life on top of still water. Water striders use the surface tension of water to their advantage so they can “walk on water”.

Water acts different at the surface. Water molecules are attracted to each other, and like to stay together, especially on the surface where there is only air above. The attraction between water molecules creates tension and a very delicate membrane. Water striders walk on this membrane.
The secret of the water strider is its legs! The legs have tiny hairs that repel water and capture air. By repelling water, the tiny water striders stand on the water’s surface and the captured airs allows them to float and move easily.

Water striders are about a half inch long with a thin body and three sets of legs. A water strider’s front legs are much shorter than the two sets of back legs.

The shorter legs are used for catching and holding onto food. Water striders eat insects and larvae on the surface of water, such as mosquitoes and fallen dragonflies.

Habitat and Range: Look for water striders on the surface of calm or slow-moving water throughout the continental U.S. They prefer ponds, vernal pools, and marshes.

Fun Fact

Scientists are studying the legs of water striders in hopes of making materials that easily repel water and help objects move faster over water.